ChromaTalk Archives: December 2005
- A Replacement Chroma CPU Board - PLUS a whole lot more. Introducing the Chroma CPU Plus (CC+) (45 messages)
- Impact of Keyboard Article on Site Visits
- Chroma behaving strangely (4)
- Dead Main Out
- Patch Conversion Tools for Mac OS X
- No. 21030734 Back to life (2)
- PolyAftertouch Kit: Worth it or not? (2)
- Re: Rhodes Chroma cassette interface... (4)
- Chroma for sale in the UK (5)
A Replacement Chroma CPU Board - PLUS a whole lot more. Introducing the Chroma CPU Plus (CC+)
David Clarke [21030085++] · Thu, 01 Dec 2005 18:57:33 -0500
When you're sitting down to decide whether you've been naughty or nice, and what items should go on your Christmas list (for this year, or for next), you might want to check out the addition to the Rhodes Chroma site for December.
If you're wanting to recover from a bad case of acid damage, add MIDI, add a larger (external) display or just wish to avoid changing those batteries ever again - take a look at The Chroma CPU Plus (CC+).
Let us know what you think, and please feel free to pass along your thoughts in terms of what features are most desired for future firmware releases.
Happy Holidays
Paul Hackett-Evans [21010094] · Thu, 1 Dec 2005 23:08:53 -0000
CC+ Board
Sandro & David,
I just read the new page on the Chroma site about the CC+ board.
WOW!! Fantastic! I think I'm going to want one of these!!
Does the MIDI implementation overcome the Chroma Cult one, where programs 46 49 are unavailable if the MIDI converter is plugged in? [See The Special Functions in the Syntech/Chroma Cult manual.]
I have a question about software patch editing I use Emagic SoundDiver as my patch editor/librarian for the Chroma. The Chroma module in SounDiver was written (I think) by Malte Rogacki [21010091], and works perfectly with a standard Chroma using a Chroma Cult Midi Converter.
Will the CC+ Board-equipped Chroma still be editable and librarian-able via SoundDiver?
I guess if necessary, since the CC+ board leaves the Chroma port available and it can be used with the Chroma Cult interface, maybe so. But it would be elegant if SoundDiver could access the Chroma still using the CC+ MIDI interface. Will the extra banks of memories and any other additional features mean the SoundDiver Chroma module won't work, since it looks for a single bank of 50 programs?
I wonder if Malte would consider updating the Chroma module for SoundDiver to accommodate the CC+ new features.? Should be possible, since SoundDiver is modular in nature.
Next It sounds as if a CC+ equipped Chroma, with a modern switching power supply, would be the way to go. The original power supply is surely the Chroma's achilles heel. A truly reliable Chroma, with modern control circuitry is a very nice idea. Will the reduced power needs of the CC+ board mean that a different spec of switching PSU is recommended? Sandro, is the design of your auxiliary board to the Switching PSU available anywhere? Would you make them to order?
AND. Whats the C2 going to be??? Are we talking about a Chroma equivalent module, using the CC+ board and voice cards built using modern (Ii.e. readily available) components? Now that would be something! I know CC+ obviously doesnt produce sound of itself, so Im guessing that C2 must have some Chroma-related modern voice-card capability.
David, I know youve made a set of voice cards for yourself and published the plans, is a modern equivalent possible, or does the sound of the Chroma depend on the CEM chips? Could that mean modern replacements for the Chromas original voice cards is a possible future project of yours?
Lastly, for now, The beauty of the Chroma for me lies in its sound and its unique keyboard, which is a joy to play, and a big part of the reason I never parted with my Chroma through thick and thin. I'm in favour of updating the innards using modern components that give the same sound with modern reliability. I'm also in favour of new features and even new sound creation possibilities, as long as the original sound of the Chroma is not lost along the way. As for the keyboard, hows about someone producing a modern keyboard pressure sensor, too???
This email is turning into a wish-list!
But seriously, guys, well done on the CC+ board, it looks stupendous!
Jim Russo [21030433] · Thu, 1 Dec 2005 19:10:34 -0500
Absolutely F'in Incredible! Put us down for two!!! Bravo!
Ben Vehorn [21030757] · Thu, 1 Dec 2005 20:02:46 -0500
So are these available now?
I didn't notice a price, did I miss it or can you provide one?
Looks very nice. I imagine that if one's Chroma doesn't have the "nuclear" power mod, this might make it a bit more stable as it draws a lot less current. I'm sure I'll pick one up if they are reasonable.
You should make a run of the knob boxes as well! It kills me every time I read the "I didn't think too many people would be interested in paying $400US or so for a box" line because I think I'd pay that in a second!
BTW, has anyone created a Chroma template for the Behringer BCR2000? I have a BCR for this purpose but I'm too much of a midiphobe to program it so far. Maybe one day...
Tom Klepacki [21030025] · Thu, 01 Dec 2005 20:32:06 -0500
The burning question will be... Tah Dah.... How much will it cost? It's gotta be cost effective, meaning, if it costs x, then will the street value of the instrument increase by x....? It can't be like over-improving your house, relative to the neighborhood.
Availability/ production runs...?
If the numbers make sense, I want one!
David Clarke [21030085++] · Thu, 01 Dec 2005 22:40:41 -0500
Re: CC+ Board
Paul - a few answers:
Does the MIDI implementation overcome the Chroma Cult one, where programs 46 - 49 are unavailable if the MIDI converter is plugged in?
This limitation should only exist with Revision 12 of the Chroma firmware (ref: "The Special Functions" section on on the Syntech/Chroma Cult manual).
Even without the CC+, if you wanted to update to the more current firmware (Rev. 14) you should be able to get your upper programs back. The images for Revision 14 are available from the Chroma site and can be programmed into the EPROMs on an existing Chroma. (There's also a set of Rev 14 images there that can be used in an Expander).
With regard to MIDI, the CC+ will behave more like the Revision 14 firmware + Chroma Cult interface (in that you'll have full access to the bank of patches.)
[The original Chroma Cult restriction came from the fact that the CPU had to be able to send 'special commands' to the external MIDI interface via the Chroma port. With the CC+, the MIDI support is built right into the CPU code - so no such external command restrictions exist.]
I have a question about software patch editing - I use Emagic SoundDiver as my patch editor/librarian for the Chroma. ... Will the CC+ Board-equipped Chroma still be editable and librarian-able via SoundDiver?
I think (although I'm not certain) that SoundDiver gets/sends its patch banks via MIDI SYSEX dump/request.
The CC+ can send/respond to the same SYSEX that the Chroma Cult/Syntech interface can. From that perspective, I think it will probably work natively.
Because we do have full control over the MIDI implementation and source - if we did find that there was something slightly different required to support SoundDiver, we'd pretty much just need to know what that is and it could be added.
Will the extra banks of memories and any other additional features mean the SoundDiver Chroma module won't work, since it looks for a single bank of 50 programs?
In its basic form, the idea is to have the CC+ make itself look to the outside world as a 'standard' Chroma - so the extra banks or features should not negatively impact on devices talking to the keyboard.
...It sounds as if a CC+ equipped Chroma, with a modern switching power supply, would be the way to go. The original power supply is surely the Chroma's achilles' heel.
Ah, you've hit upon a bit of a philosophical. Some folks feel strongly that the old power supply has to go (and the sooner the better) - while others are content to leave the original in place.
I tend to be of the "if it's currently working, leave it alone" school of thought.
My keyboards use the original CPU power supply. Sandro is using a more modern switching supply (ref: How To Swap The Original Power Supply With A Readily Available Switching Unit)
The CC+ works equally well with both these setups.
Will the reduced power needs of the CC+ board mean that a different spec of switching PSU is recommended?
In addition to their 'max current' capability, many (most/all) switching power supplies also have a 'min current' requirement, since a certain load is needed to have switcher 'work'.
The CC+ does drop the draw on the 5V rail signficantly (by essentially an ampere). The other circuitry in the keyboard will still be pulling over an amp from the power supply on that rail though (i.e., we will have dropped from 2+ amps down to 1+ amp).
As long as the remaining draw exceeds the minimum draw required from your chosen switching power supply, all should be well.
The T-60B Meanwell supply referenced by Sandro in his article (noted above) seems to be spec'ed with a min. draw of 0.5Amps on the 5V rail.
If I properly read the data for the MAP80-4000 (referenced in Don Tillman's Nuclear Powered Chroma writetup), then that power supply may need a minium load of 1 amp. The lower power draw of the CC+ may get the +5V rail near that - so that may sway you towards a model that has a lower min. power draw. (Generally speaking, the higher the max power capability of the switcher, the higher the min load required).
AND. What's the C2 going to be???
Ahhh - if we said that now, it wouldn't be a surprise later, would it? :->
...As for the keyboard, how's about someone producing a modern keyboard pressure sensor, too???
This question has come up a few times.
The 'tough' part is the pressure-sensitive pads (ref: Q6 in the Pressure Sensor & Interface Q&A).
If we could find material (or sensor) that ouputed an electrically detectable signal (voltage/resistance/current, etc.) in response to the pressure range you'd want for the interface, then you'd be all set (the poly pressure bar is not much more than the pressure sensitive elements, and a small amount of electronics to scale the electrical signals to a sandard value the I/O board wants to see.)
Of course, the sensor would also have to be inexpensive enough to make it viable.
Tom Moravansky [21030431] · Thu, 1 Dec 2005 17:54:41 -0800
I'll take one as soon as they are ready. Cost doesn't matter.
As far as more features - I'd say, just get the board out initially with the specs you have and then take some time to evaluate the feature requests from the community. Once you have a good batch of features, then do a software upgrade.
2 cents from a Chroma owner with battery damage....
Mark W. Holbrook · Thu, 1 Dec 2005 20:09:13 -0700
Whoa!!
Oh.... My....
After the new power supply, new voice card design, and now the CPU Plus, the obvious next step would be a new Chroma sound module design. C2?
As far as I know, this is unprecedented in the synth world.
I have been without a Chroma for far too long, hesitant to jump back in because of the maintenance requirements. I thought that my best hope would be a virtual emulation from a company like Arturia. But now this has me overwhelmingly intrigued.... You probably don't want to spill the beans too early, but if this is a Chroma module, count me in for a C2, or 2, or 3....
Ron Joseph [21030042+] · Fri, 02 Dec 2005 03:36:48 +0000
I'll definately be taking one. As for the knob box, I'd gladly pay $400+ for the ability to program without menus. An alphanumeric display? You guys are too much. "Making a great board even better"
Åke Danielson [21010068] · Fri, 2 Dec 2005 08:46:13 +0100
This message didn't get through to the list because it was sent from a non-subscribed address, but I thought I'd include it here in the archives.
Been on the waiting list for a long time and still am. Ready when you are!
Thorsten Pörschke [21030734] · Fri, 02 Dec 2005 09:28:46 +0000
Hello David
when will the board be availble (Q1 2006, Q2 2006, Q3 2006)?
Thorsten Pörschke [21030734] · Fri, 02 Dec 2005 08:55:16 +0000
Hello David and Sandro
You did an awesome job again, making good even better. Count me in for one.
Malte Rogacki [21010091] · Fri, 2 Dec 2005 11:17:10 +0100
Re: CC+ Board
I have a question about software patch editing I use Emagic SoundDiver as my patch editor/librarian for the Chroma. The Chroma module in SounDiver was written (I think) by Malte Rogacki, and works perfectly with a standard Chroma using a Chroma Cult Midi Converter.
Will the CC+ Board-equipped Chroma still be editable and librarian-able via SoundDiver?
I guess if necessary, since the CC+ board leaves the Chroma port available and it can be used with the Chroma Cult interface, maybe so. But it would be elegant if SoundDiver could access the Chroma still using the CC+ MIDI interface. Will the extra banks of memories and any other additional features mean the SoundDiver Chroma module won't work, since it looks for a single bank of 50 programs?
I wonder if Malte would consider updating the Chroma module for SoundDiver to accommodate the CC+ new features.? Should be possible, since SoundDiver is modular in nature.
As long as the Chroma board follows (more or less) standard procedures MIDI-wise it should be pretty trivial to make the changes. SoundDiver support is done by an adaptation, not a module. This means that anybody can change the adaptation to suit different needs. If the new board should contain a radically different MIDI implementation I'm willing to assist in all SysEx questions.
Luca Sasdelli [21010226] · Fri, 02 Dec 2005 11:56:59 +0100
Re: CC+ Board
Hi Dave & Sandro,
I'm really amazed by the switching from the "old" project to the brand new one!
A question: what about the external display? Are there already some compatible models, and/or microprogram routines to drive them, or is it a software section to be written from scratch?
Anyway, if you carefully look at the long queue just out of your door, you'll see me too ... :-)
Mal Meehan [21010182++] · Fri, 2 Dec 2005 14:27:38 +0000
This message didn't get through to the list because it was sent from a non-subscribed address, but I thought I'd include it here in the archives.
Boys.
This sounds great . . . I'll take 3!
Are we going to see a little Chroma rack with knobs on the front in the future?
Yes please!
Jack Colburne [21030142+] · Fri, 2 Dec 2005 10:34:05 -0500
Been away.. just got back...and found...
The Chroma CPU Plus (CC+): Bravo, Sandro and David. Sincerely, bravo.
It's not as easy as one might think to find a true example of a labor of love. This is clearly one. (There are actually several highlighted on this site) I don't even want to speculate on your C2. I'm a very patient man.
a MIDI question: Please forgive me if I missed this in the documents...
The Syntech interface does not allocate voices to MIDI channels dynamically. It must recieve a Program Change #0 on each MIDI channel used in order to free up the voices. How will the MIDI interface on the CC+ handle voice allocation when used as a multi-timbral sound souce?
Jim Russo [21030433] · Fri, 2 Dec 2005 12:37:41 -0500
Dave,
Does the Chroma sound EXACTLY the same with the CPU in there ??
Mike Jaynes [21030638+] · Fri, 2 Dec 2005 22:05:55 -0500
Re: CC+ Board
Hi;
When figuring your build, put my name in for one. I know the price of the build is heavily influenced by quantities so I would recommend for anyone that is "for sure" interested in the CPU board, let David know so he can plan accordingly.
David Clarke [21030085++] · Fri, 02 Dec 2005 23:48:17 -0500
From: "Jack Colburne" a MIDI question:
The Syntech interface does not allocate voices to MIDI channels dynamically. It must receive a Program Change #0 on each MIDI channel used in order to free up the voices. How will the MIDI interface on the CC+ handle voice allocation when used as a multi-timbral sound souce?
Jack - if you're referring to what I think you are, then we can't necessarily blame the Syntech interface as the MIDI/Chroma Port interface does not actively particpate in the allocation of voices (per se) - that's a low-level firmware responsibility.
The handling of board and voice-allocation is discussed in the "Board Allocation and Channel Assignment" section of the Chroma Computer Interface Manual.
In summary, the internal structure of Chroma works on the concept of an 'instrument.' Up to 8 instruments can be defined at any one time. Each instrument is defined by a given program - and the characteristics of that program (poly, mono, etc.) dictate what sort of voice/channel resources that instrument wants/gets.
If you define 1 instrument only (lets call that instrument 0) - then up to 16 channels are available.
If a second, instrument is defined - then just the process of defining the second instrument will change the overall number of channels available. In this case, instrument #1 might have 8 channels available to it, with the second channel having 8 channels available to it.
The Chroma will try to treat these as two separate, logical 'instruments'. For instance - running out of voices/channels on instrument 0 can't/won't affect instrument 1. Looking at this from another perspective, even if instrument 1 isn't 'playing' any of its 8 channels, these are still effectively 'off limits' to instrument 0. There is no voice stealing or sharing between instruments.
So - the comment in the Syntech manual about a '0' Program change is really there to try to limit the number of instruments that are defined at any one time (thus ensuring the greatest number of voices are available in the voice pool for the remaining instruments).
The general rule of thumb really would be to use as few number of 'instruments' as you can (so that the most number of channels/voices stay available for individual instruments).
(I might have rambled on a bit. If this didn't make sense, just let me know).
Jesper Ödemark [21010135] · Sat, 3 Dec 2005 08:10:11 +0100
Re: CC+ Board
I'm interested... stilled stunned about the news though! =)
Not as "techie" as many of the other guys I'm mainly interested in the discussed way of adding an external midi control box to allow tweaking via midi...
Thorsten Pörschke [21030734] · Sat, 03 Dec 2005 08:23:57 +0000
Re: CC+ Board
I also would recommend that everybody who "orders" has to pay in advance. Since I did once a business with David I know he is a very relaible and honest guy.
Werner Schöenenberger [21010114] · Sat, 3 Dec 2005 09:58:54 +0100
Re: CC+ Board
Hi all,
this is great news. I am also interested in the CC+. It is wonderful that after dozens of years, the Chroma is revived again. Great.
Ron Joseph [21030042] · Sat, 03 Dec 2005 20:50:32 +0000
CC+ Board & knob box wish
The idea of paying in advance sounds perfect. That way there's chance that the guys will get stuck w/ "extra boards " because of non payment. Just waiting to know how much and where to send the check. (or other form of payment, whatever easiest for you guys). Is there ant chance of getting you to reconsider making a run of knob boxes based on the same pay in advance order strategy? I'm sure you'd have a bunch of takers. (My heart beat skips a beat just thinking of it :) )
Olli [21010284] · Sat, 3 Dec 2005 23:28:34 +0100
Re: CC+ Board & knob box wish
CC+
all i can say is maximum respect for this initiative. bravo! C2... am i curious... :-)
Rob Vandivier [21030396] · Sat, 03 Dec 2005 18:42:20 -0500
Re: CC+ Board & knob box wish
I'd buy one right now thanks.
Vincent Russo [21030433] · Sat, 3 Dec 2005 21:33:58 -0500
C2 Guessing :)
Thought we could have some fun.......
- External Audio Input to Chroma Filters, and or other ?
- Voice Expansion board ?
- FM or other synthesis add on or additional Synthesis capability?
- NASA Mission control module : o
- Chroma Multi Timbral board ?
Edward Chen [21030674] · Sat, 3 Dec 2005 17:50:29 -0800
Re: CC+ Board & knob box wish
Count me in too along with the control box if and when you ever decide to make a run of it! : ) Happy Holidays!
David Clarke [21030085++] · Sat, 03 Dec 2005 23:13:16 -0500
CC+ Comments/Questions/Availability, etc.
Taking into consideration the start of the holiday season, a busy time at work and the desire to spend a little time watching the play-downs for the Olympic curling team [archive.org] - OK, it's probably only a Canadian thing ...), I may be a bit slower in responding over the next while.
With regard to the CC+, our main emphasis was to have the initial board and software up and running for the end of the year. As we achieved that early - the next goal was to have the article up and avail. for December. That article has been well received. (thank you!)
In addition to doing our 'real work' (i.e., our day jobs that pay the bills) we're also dotting the "i's" and crossing the "t's" for the board and the associated interfaces.
Please feel free to ask any questions you might have on the CC+ and we'll certainly respond as we can.
We will (of course) be getting back to the list in the not too distant future with details on cost/availability. The amount of interest already expressed does help us to guage the relative numbers we might be looking at (which lets us better understand what the costs will be).
All the best,
David Clarke
David Clarke [21030085++] · Sat, 03 Dec 2005 22:44:52 -0500
Knob Box Wishing
Wow! I honestly didn't think there would be that many folks who really would want a knob box (esp. if you were looking at $400+ and also considering that some knob functionality can be given with standard MIDI knob boxes, etc.)
The box itself isn't technically difficult - so given the apparent interest, I can't rule out at some time maybe making some up.
This wouldn't happen for the next while though, as CC+ will be taking the short-term priority (and of course, we're now getting into the Holiday season).
Once CC+ is totally taken care of, we can revisit this (and see who'd really be interested, etc.)
Jack Colburne [21030142+] · Sun, 4 Dec 2005 01:49:55 -0500
David, this is a very good explanation of exactly to what I was referring.
the Syntech interface ...does not actively particpate in the allocation of voices (per se) - that's a low-level firmware responsibility. Gotcha. That makes sense.
Bear with me... :-)
I understand the Chroma Instruments & channels concepts, etc. I read thru the Interface manual... but what I'm not clear on is if we need to, actually, manually un-define the instruments. Assuming all are polyphonic, non-split programs, if I send a PrgChg to (base) MIDI channel 1 and play 3 notes, then send a PrgChg to MIDI channel 2 and play 3 notes, I've defined 2 instruments and assigned 6 boards. I'm left with 2 unassigned voice boards. Will I still need to send that PrgChg "0" (which is, basically, the live editing patch) in order to free up those boards or will the machine act as a more "modern" module and "automatically" free the voices for other instruments?
I just realized that I'm asking for a fundamental change in how the Chroma interface processes performance data, and that's not the goal here. But questions are still the the best way to learn.
And David, your advice on limiting the # of instruments is still the best. The Chroma fits well in a situation where you need a bass line (mono), and a handful or 2 of sound. 3-4 notes of Chroma can go a long way to fill space.
Just think... next year we talk Sandro and David into designing a 64 note polyphonic Chroma to fit in 4 rack spaces. Yeah!! (kidding)
Jesper Ödemark [21010135] · Sun, 4 Dec 2005 10:33:21 +0100
Re: C2 Guessing :)
Wish list:
- Knobs (for everything)
- Aftertouch (only reason for keeping my old sampler)
- B-A-N-D-P-A-S-S filters! Why not a whole bunch of them for those vocal sounds...? =)
Jesper Ödemark [21010135] · Sun, 4 Dec 2005 10:44:15 +0100
Re: Knob Box Wishing
You and I have been talking knob boxes before David, but I put aside the ideas of one once you mentioned the board you were working on would allow control over most (all?) setting from a standard knob box. This is my main interest, to tweak stuff more easily and in realtime if possible.
A few notes (dummy-style) on how this would work would be much appreciated... A "Externally tweakable Chroma for dummies" so to speak...
I only use midi since it's most convenient, the majority of my synthesisers are "cv-gaties..." so midi CC-messages etc are a jungle to me. Just to change the midi channel in my retro-fitted PS-3200 (now sold...) took me an afternoon to figure out... :(
Vincent Russo [21030433] · Sun, 4 Dec 2005 11:23:29 -0500
Re: Knob Box Wishing
Another vote for the Clarke knob box, perhaps he could offer them non finished so we could stain them to match are refinished Chroma's ? Down the road of course. I would prefer Dave's design much over any commercial offering out there. Coming from someone who does really mind the Chroma programming as is either.
Vincent Russo [21030433] · Sun, 4 Dec 2005 11:30:18 -0500
Re: C2 Guessing :)
- B-A-N-D-P-A-S-S filters! Why not a whole bunch of them for those vocal sounds...? =)
You can simulate this on the present Chroma by creating sidebands using the patch mode and one of the variable mix Filter modes.
We have vocal like patch and several electronic choirs sounds in are new patch bank which will be available to list members for free next month on the site.
David Clarke [21030085++] · Sun, 04 Dec 2005 11:15:39 -0500
Re: Knob Box Wishing
...A few notes (dummy-style) on how this would work would be much appreciated... A "Externally tweakable Chroma for dummies" so to speak...
Jesper - the Syntech MIDI interface currently makes some of the Chroma parameters accessible via MIDI continous controllers (These are listed in the MIDI interface manual in TABLE 1: Chroma Parameters to MIDI Controller Translations.)
With reference to that table, any parameter which has an entry in the "MIDI Controller Number" column can be controlled externally via MIDI.
If you have a MIDI fader/knob box which allows you to assign the functions of the selections, then setting up that box to the controller numbers listed is essentially all that's required in order to allow the Chroma to be 'tweakable.'
(The CEB and the CC+ goes a bit further and allows all of the parameters to be reached via CC's over MIDI.)
David Clarke [21030085++] · Sun, 04 Dec 2005 11:07:54 -0500
Bear with me... :-)
... I'm not clear on is if we need to, actually, manually un-define the instruments. Assuming all are polyphonic, non-split programs, if I send a PrgChg to (base) MIDI channel 1 and play 3 notes, then send a PrgChg to MIDI channel 2 and play 3 notes, I've defined 2 instruments and assigned 6 boards. I'm left with 2 unassigned voice boards.
Jack - the behaviour that makes the 'undefine' necessary is that the Chroma has a separate process to allocate voices vs. assigning them.
The 'allocation' routines really only cares about the number of instruments defined, and the type of patch used to create the instrument.
The 'assignment' routine doles out voices from the number of channels available in an instrument.
If you start from scratch (no instruments defined) - and send a PrgChg to (base) MIDI channel 1, then even before you play any notes - the Chroma would allocate all of the channel boards to that instrument. You can now play 8 (or 16) individuals notes without worry.
When you later send a PrgChg to MIDI channel 2, the Chroma realizes that you now have two instruments - both with polyphonic patches.
The allocation routines say "OK - you fellas are going to have to share the total number of boards. To be fair, one instrument will get half of the boards (4) and the other instrument will get the other half (4 boards)."
Insofar as the Chroma is concerned, at this point all of the boards are allocated (with none 'left over').
When you start to play notes, it is the assignment routine which comes into play - and voices can only be assigned within the number of boards allocated to an instrument. (The assignment will never 'steal' from another instrument, as you wouldn't want your piano patch to steal all the voices away from your brass patch, etc.)
For instance - when you go to play 3 or 4 notes on the first MIDI channel, you're OK (since you have 4 boards assigned). When you go to play your 5th note (or 9th note, if 16-voice mode is used) then you will have run out of free boards, and the voice allocation routines will have to steal from an already sounding board among the 4 allocated to that instrument.
Consider the worst case where you have the MIDI interface set up to support 8 instruments (e.g., Parameter 5, "Instruments Available" from the Syntech programming mode, set to 7) and the MIDI base channel set to 1 (P1 setting of the Syntech interface set to 0).
Now lets consider that the sequencer sends the following:
- PrgChg to Patch 11 on MIDI Channel 1
- PrgChg to Patch 12 on MIDI Channel 2
- PrgChg to Patch 13 on MIDI Channel 3
- PrgChg to Patch 14 on MIDI Channel 4
- PrgChg to Patch 15 on MIDI Channel 5
- PrgChg to Patch 16 on MIDI Channel 6
- PrgChg to Patch 17 on MIDI Channel 7
- PrgChg to Patch 18 on MIDI Channel 8
If we assume that Patches 11-18 are all poly (unlinked) patches, then we will have defined 8 instruments - and all those instruments will have been assigned 1 board each (assuming all 8 boards passed auto-tune).
Even though these patches are defined as polyphonic - they will effectively play like a mono patch - as there can only ever be one board assigned to it.
By undefining an instrument (e.g., a ProgChg 0 on that channel), you free up any boards that were assigned to it - and allow those boards to be reallocated to the remaining instruments.
Will I still need to send that PrgChg "0" (which is, basically, the live editing patch)
The MIDI interface uses a 'change to program 0' message to send an indication to the Chroma to "undefine the instrument I had defined on this channel." (i.e., it is a special case - it doesn't actually do a program change, it translates the MIDI PrgChg 0 message to be a Chroma interface 'undefine' command).
...The Chroma fits well in a situation where you need a bass line (mono), and a handful or 2 of sound. 3-4 notes of Chroma can go a long way to fill space.
In a case like this, if the bass line program is really defined as a mono patch - then the Chroma will only ever assign it 1 board. That means if you have one other poly patch defined, that that poly patch will still have access to 7 boards (7 notes or 14 notes, depending on the voice architecture chosen).
... of course, if still you find yourself running out of voices, you can always pick up a 2nd (or 3rd, or 4th) Chroma :->
Jack Colburne [21030142+] · Sun, 4 Dec 2005 14:02:36 -0500
Ah... I get it. Excellent, thank you David. I understand perfectly. Very clear explanation. It's not so mysterious at all....
(the Chroma) translates the MIDI PrgChg 0 message (sent from the MIDI interface) to be a Chroma interface 'undefine' command.
Now, that makes sense. I just read thru the Sequencer manual for the first time...it also makes much of this clear.
"Voices" are allocated on a first come first served basis... meaning that the lower instruments (the first ones defined) will have priority over later instruments.
with all polyphonic non-patch #0 programs...
- PrgChg to Patch 11 on MIDI Channel 1 = 3 voices
- PrgChg to Patch 12 on MIDI Channel 2 = 3 voices
- PrgChg to Patch 13 on MIDI Channel 3 = 2 voices.
The Apple sequencer sends a Define comand at the start of each track and an Undefine command at the end of each track so that ending a partiicular track (kbd part) in the middle of the sequence will free up the allocated voices for the other defined instruments. I'm willing to bet that it sends Undefine commands to each instrument whenever the sequence playback is stopped as well. I understand now... it would be impractical to expect the Chroma to learn how to dynamically allocate voices and would take a complete redesign/rewriting of the system and, probably, a heck of a lot more computing power. Undefining instruments every time note-off commands equal note-on commands to free up voices on a particular MIDI channel would, right now, entail constantly redefining that instrument ... PrgChg and all.
And besides, I do have a second battered Chroma that was supposed to help keep the first alive. But now, with your and Sandro's work, they probably can both be kept alive. :-)
thanks again, David
Daniel Benoit [21030109] · Sun, 04 Dec 2005 21:18:01 -0500
CC+ Board want one
Hi Dave
Count me in for a CC+
Chroma owner in Monteal
David Gowin [21030611] · Mon, 05 Dec 2005 09:09:52 -0500
Re: CC+ Board & knob box wish
I'm in! Be more than happy to pay in advance (as long as the build time is relatively reasonable).
Rob Vandivier [21030396] · Mon, 05 Dec 2005 11:14:47 -0500
Re: CC+ Board & knob box wish
Or maybe a deposit? This knobbox would be a godsend to me. Im not so good at wiring and soldering. BTW does anyone know what would be the most probable diagnosis/remedy for a dead main output? The individual outs work but the main mix out doesn't.
See Dead Main Out below.
Jerry Leonard [21030100++] · Mon, 5 Dec 2005 11:58:11 -0800
For planning purposes, I'll take three.
Luigi Castelli [21030825] · Mon, 5 Dec 2005 14:09:57 -0800
I want 2 of them. Let me know when they are ready.
Great job!
Jesper Ödemark [21010135] · Tue, 6 Dec 2005 08:22:04 +0100
Re: CC+ Board & knob box wish
BTW does anyone know what would be the most probable diagnosis/remedy for a dead main output? THe individual outs work but the main mix out doesnt.
Most probable is a loose cable/worn socket...
John B. Rotondi [21030185+] · Tue, 6 Dec 2005 02:12:28 -0800
Dear Chroma Friends,
Congratulations to David and Sandro on the development of an upgrade CPU for the Chroma!
I have 2 Registry Chromas in storage at this time. Some time in the next year, I am hoping to completely go through both and bring them up to snuff mechanically, electronically, and cosmetically. I'll probably keep one, and sell the other at that time.
Of course I will want to add the new CPU to each, so will want to order 2, probably in mid-2006, FYI.
Also, thanks to all the contributing Chromaphiles (I think I just invented a new term- feel free to use it!) for these continuing developments- and my sincere thanks to Chris Ryan for his diligence and dedication in preserving the heritage of this landmark instrument via his fabulous Rhodes Chroma website!
Finally, Happy Holidays and a Great New Year to All!
Sandro Traversi [21010217] · Mon, 12 Dec 2005 23:56:00 +0100
Re: Knob Box Wishing
Another vote for the Clarke knob box, too.
A kit w'd be good to me.
Impact of Keyboard Article on Site Visits
Chris Ryan [21030691] · Thu, 1 Dec 2005 23:47:52 -0800
When Mark Vail's Chroma article (Chroma: The Synth that Survived ARP's Fall) was announced for the October issue of Keyboard, David Clarke wondered what the impact would be on site activity. Now that November is past I thought I'd take a look at the site statistics to see if I could find an answer. Overall it is quite difficult to discern the impact, as there is (obviously) no referring site string in log files for manually entered URLs. In addition, site activity fluctuates and, in general, grows gradually all the time--and the new site is still ramping up slightly as the remaining links to the old site are slowly changed around the Web.
I've analyzed site log files for September, October, and November, which aligns roughly to the period immediately before, during, and after exposure of the Chroma site in Keyboard and on keyboardmag.com. I used Sawmill for log file analysis.
During these three months, 8,654 visitors viewed 55,426 pages at rhodeschroma.com.
Only 89 visitors (1 percent) linked from keyboardmag.com during this time. This activity was almost all between October 12 and November 11, presumably corresponding to the time during which the article was featured on the "current issue" page of their site. (Looking at the log files, the several hits prior to October 12 seem to have been the result of internal testing of the link.) The Chroma article [since revised, with pictures and links back to this site removed] with link remains on keyboardmag.com, but is more difficult to find; from November 12 to 30, only four people reached rhodeschroma.com from the Keyboard site. The following graphic shows visitors referred from keyboardmag.com during October and November (there were none in September).
In comparison, the top referring site during these three months was fenderrhodes.com, with 334 visitors; synthzone was next with 251. In terms of search engines, well over 3000 people came from Google sites (various countries, and Google Images).
Overall there was an upward trend in the number of visitors to the site:
- 2898 - September
- 3318 - October
- 3642 - November
Assuming that the news stand availability of the October issue of Keyboard corresponded approximately to the period in which it was the "current issue" on their Web site, it is difficult to see that the print article had any obviously significant impact on the Chroma site, as the trend has continued generally upward throughout November. The following graphic shows daily visits; the shaded area indicates the period on which the October issue was current on keyboardmag.com and the magazine was probably available on news stands.
I don't know what the circulation of Keyboard might be, but it seems less popular, and more difficult to find, than ten or twenty years ago. It's interesting to note that more people reached rhodeschroma.com from Don Tillman's site (Electronic Music Articles and ARP Synthesizers pages) than from the Keyboard site over the past three months. This indicates to me that people search the Web for good information, rather than rely on "authorities" from the print era.
It will be easier to judge any real impact given a longer view, when October 2005 statistics can be seen in the context of multiple preceding and following months, and compared with October 2006, for example. In the grand scheme of things I suspect, though, that the magazine article has had little relative impact on the Chroma site other than generating a bit more awareness. And I'm sure that people will, from time to time, dig out the October 2005 issue and take a look at the site as a result of seeing the article.
In the long term, the Keyboard article seems to have had little direct impact. See Site Statistics for more information.
Chroma behaving strangely
Tim Siefkes [21030850] · Sat, 03 Dec 2005 04:49:14 -0600
With thanks to Martin Straw [21010093+] in the UK for the part, I was able to get the channel motherboard replaced in my Chroma. (I had accidentally broken the pins on the ribbon cable trying to remove the top section of the Chroma for foam rot cleaning.)
Now with the Motherboard replaced, I can at least get a sound out of it again, but not what I expected. In my process of working on it I had left the batteries out overnight and therefore I've lost all the programming of the voices. So, trying to rebuild even a single voice starting with the "scratch patch", I can now get a tone to come out, but the keyboard scaling seems very off. Each half-step interval I play on the keyboard results in a whole step pitch difference. It's as if the whole keyboard is stretched by a factor of 2, giving me a ten-octave range but no half-steps. Not very useful. Anyone ever experience this or have an idea what it might take to get this tracking properly again?
Once I get this up and running, the CC+ is something I'll be in line for as well. Thank you.
David Clarke [21030085++] · Sat, 03 Dec 2005 23:46:07 -0500
Now with the Motherboard replaced, ...I can now get a tone to come out, but the keyboard scaling seems very off. Each half-step interval I play on the keyboard results in a whole step pitch difference. It's as if the whole keyboard is stretched by a factor of 2, giving me a ten-octave range but no half-steps...
Tim -I'm not aware of any 'normal' setting which will give you this sort of keyboard stretching.
A few questions to narrow down what might be occurring:
- do all the voices seem to function this way - or just some?
- when the keyboard is turned on - do you see all of the LEDs flash off and on (16 times) - or does the panel immediately go to display the program number?
- if flashing is seen - how fast do you see it blinking? (a good measure would be, how many seconds does it take for the 16 blinks to occur?)
Jack Colburne [21030142+] · Sun, 4 Dec 2005 01:23:29 -0500
Tim -I'm not aware of any 'normal' setting which will give you this sort of keyboard stretching.
Actually, I believe there is. Parameters 27 thru 32 control the oscillator's response to, among other things, the Keyboard Glide. Parameter 27, 29, and 31 set the source of the modulation and 28, 30, and 32 set the corresponding mod amounts. Parameters 31 and 32 are worth looking at in particular... the scaling on #32 mod amount sets the modulation scaling in semi-tone increments. You can use these modulation sources to stretch or shrink the osc. response over the keyboard and get the keyboard to play an octave of over the entire keyboard, or to play several octaves of pitch over a single keyboard octave. If I remember correctly, you can even turn the keyboard upside down. (very useful stuff for "sync" or "ring-mod" programs.) And combinations of mod sources can give some very strange results.
Maybe it's worthwhile checking these modulation sources.
Sounds like a weird thing to suggest, but you also might try playing around with the pitchbend and mod levers and the foot controller in case they need to be re-set somehow.
All of David's suggestions and questions make sense... I don't know what would cause this to happen across all the patches. I remember that the velocity scaling changed between revisions, but I'm not aware of anything that ever affected the keyboard glide (Chroma unit) scaling.
Chris Ryan [21030691] · Sun, 4 Dec 2005 00:27:24 -0800
If I remember correctly, you can even turn the keyboard upside down.
Yes, you can. It's really interesting to play such a patch. Joe Zawinul mentioned this feature in his endorsement of the Chroma.
Dead Main Out
In response to Rob's question above.
David Clarke [21030085++] · Tue, 06 Dec 2005 22:23:10 -0500
BTW does anyone know what would be the most probable diagnosis/remedy for a dead main output? THe individual outs work but the main mix out doesnt.
Rob - the quick differentiating test will be to see if the main out (from the XLR) is OK. If it is OK, then all of the 'main out' electronics (EQ/amp) are OK.
So - if the XLR out also doesn't work, there might be an electrical problem on the EQ board.
If the XLR out DOES work (and just the 1/4" main doesn't), then I'd place my bet on the specific wire going to the 1/4" main connectors. Check to see that there's a good/solidly connected brown wire firmly attached to the back of the mono out jacks (if the power supply has ever been removed, then it is easy to accidentally have one or more of these wires pulled loose).
Good luck
Patch Conversion Tools for Mac OS X
Chris Ryan [21030691] · Sat, 10 Dec 2005 18:59:59 -0800
I've compiled David's patch tools for Mac OS X. They are available from the Patch Conversion Tools page.
To use these tools, you should be comfortable using the Unix command line (e.g. the Terminal application found in Applications/Utilities). Mac OS X is required; the tools will not run on "classic" Mac OS. They have been tested on Mac OS X 10.4.2 but should work on earlier versions. Note that they have been built for PowerPC Macs; when Intel-based Macs are released I will look into compiling them for that platform.
(Note: the .snd file produced by syx2tape may not work; let me know and I will work with David on providing a fix.)
No. 21030734 Back to life
Thorsten Pörschke [21030734] · Sun, 11 Dec 2005 15:43:39 +0000
Hello
Today I finished the complete overhauling and upgrade of my Chroma. First I wanna thank David and Sandro for their great support and help within the project. Now the Chroma is back to live ;-)
Things that has be done:
- New Tolex (Fender style)
- Refurbished all wooden part's
- Upgrade PSU to SPSU
- Upgrade computer board with CEB
- Replace old opaque LED's with new transparent ones, replaced the yellow ones with blue ones
I'm not sure if it's ok to attach some .jpg to the mail so instead I'll write an email to Chris maybe he can put them somewhere (Instrument Registry) on the website.
Thorsten's pictures have been added to the registry entry for 21030734.
David Clarke [21030085++] · Sun, 11 Dec 2005 11:43:17 -0500
... Today I finished the complete overhauling and upgrade of my Chroma. ... Things that has be done: ...
- Upgrade computer board with CEB
When I built my CEB, I received two circuit boards from the board shop.
A few people on the list had shown interest in maybe getting the extra board from me.
Most of those interested folks had decided to wait for the CC+ - but for the info of those other few people, the 'other' board has gone to Thorsten (and by the sounds of it, may now actually be in use in a Chroma!)
PolyAftertouch Kit: Worth it or not?
Uro [21030401] · Sun, 11 Dec 2005 13:52:51 -0800
My model is 21030401 and I don't believe it has the aftertouch kit. I use the Chroma as my controller so, thusly, I'm considering the kit. For those who have the kit, is it worth the pain of installing it. For those who don't, would you add it? If so, who has one they can sell? :) Thanks very much.
Ben Vehorn [21030757] · Sun, 11 Dec 2005 18:10:55 -0500
I think everyone would choose to add it if they were available... very few were made and I'm guessing you will have a difficult time finding one. But good luck!
Re: Rhodes Chroma cassette interface...
Chris Ryan [21030691] · Wed, 21 Dec 2005 14:12:36 -0800
Cross-posted in response to a message on Analogue Heaven.
Has anyone had any experience with the Rhodes Chroma cassette interface at all? Rather than loading the patches using cassette tapes, I'm hooking the din connector directly in to my computer (DIN [chroma] to mono jack [computer]) - the assumption is that I just 'play' the sound patches to the Chroma.
Currently, when I click on "Load All" the machine waits, and I press play in wavelab (22050 mono signed format). The Chroma LED's light up with each patch that is loaded, but no numbers are displayed, and when it finishes I still have the previous patches. Not sure if wavelab is transmitting it at the wrong hz, or if I simply cannot upload it in this manner.
For now, I've only connected the "audio out", but ignoring the "remote", and "mic". So these could also be factors.
Any help and advice would be great :)
I have often loaded patches directly from computer to Chroma in this way. Have you verified that the cassette interface is working?
The Performance Manual says, "You will probably have to experiment to find the right settings for the volume control and tone controls (if any) on your tape deck [or in this case, computer]. Start with the tone control set to full treble, and the volume on full. Reduce the volume a little with each attempt until the Chroma reads the entire program without displaying an error." See Performance Manual: Cassette Interface.
Jack Colburne [21030142+] · Wed, 21 Dec 2005 21:21:05 -0500
Forwarded to Analogue Heaven.
Check that the "Lock/Unlock" switch on the back of the Chroma is on "Unlock". If it's locked, the Chroma will check the programs as they play, but won't load them into mempry.
David Clarke [21030085++] · Wed, 21 Dec 2005 21:17:57 -0500
Cross-posted to Analogue Heaven.
If the LEDs flash with each patch, then the data is likely being received OK by the Chroma (i.e., the flash means that the Chroma got the patch data). It is proper that you won't see any number displayed (until the loading completes).
Any chance that it is just as simple as having the 'write protect' switch flipped on the back of the Chroma?
David Gowin [21030611] · Thu, 22 Dec 2005 09:05:12 -0500
If it helps, I know loading programs using the cassette interface on the Polaris took some fiddling with volume levels before it went off without a hitch. Just my 2 cents worth.
Chroma for sale in the UK
Paul Hackett-Evans [21010094] · Fri, 23 Dec 2005 04:45:49 -0000
Not mine!
The following ad has appeared on the "Readers Ads" section of the UK music magazine Sound On Sound's website. Personally, I think the seller is rather ambitious with his non-negotiable price. But good luck to him.
Happy Christmas everyone!
Paul
Rhodes Chroma Rhodes Chroma Mint Condition for sale. Price not negotiable, Please call Paolo on: 02089864008 from 10Am to 5Pm. or write to [e-mail address removed]. £1950. Phone [removed] (LONDON, England) 15/12/05
Paul Hackett-Evans [21010094] · Fri, 23 Dec 2005 14:32:12 -0000
Paolo, the seller of this Chroma, is sending me some high-res pictures of it. I take back what I said about his being optimistic in the price, the Chroma looks to be in beautiful condition. Very desirable! I think its worth the asking price. Paolo is happy for people to try his Chroma if interested. He says its in perfect operating condition. He's in London, close to Bethnal Green Tube station.
The picture files are very big, but if anyone wants a look, please let me know and Ill send them on, once Paolos sent me the rest. The Chroma is in the registry. It's 21010175. Paolo has owned it for 2 months, prior to which it was serviced by a company called Kent in the UK, I dont know Kent at all, Im afraid. Paolo has used it in his home studio, but is selling to raise money for a deposit on a new home.
If Paolo sends me any more information, Ill let you know.
Mal Meehan [21010182++] · Fri, 23 Dec 2005 14:56:04 +0000
That's probably Kent Spong of KSR (Kent Spong Restorations).
Kent has looked at every board I have (over 30) over the last 3 years . . rebuilt a Chroma PSU for me last year.
He also does all the servicing and restoration work for Richard Lawson at rlmusic.co.uk (nice website!) and is probably the number 1 Yamaha CS-80 man in the world . . .
I have 2 Chromas going to him after the holidays for restoration.
Nice guy too.
Matrix · Fri, 23 Dec 2005 09:21:04 -0800
If Paolo wouldn't mind me hosting the shots and putting up a post on http://matrixsynth.blogspot.com, send them my way. : )
Chris Ryan [21030691] · Fri, 23 Dec 2005 11:25:07 -0800
Paul, send me the pics directly and I'll add them to the registry entry.